Apparatus for heat treating objects



i. x 7/. v i

lj /z rem Aug. 23, 1932. F. A. FAHRENWALD' APPARATUS FOR HEAT TREATING OBJECTS Filed Aug. 27. 1927 Patented Aug. 23, 1932 FRANK. A. FAHRENWALD', OF CHICAGO HETGHTS, ILLINOIS APPARATUS FOR HEAT TREATING OBJECTS Application filed august 27, 1927. Serial N 0. 215,848.

This invention relates to the art of heat treating objects, for instance, byraising the temperature of an object to a degree that will permit molecular change in the material of which the object is made and thereafter cooling the object, under such control as to the time in which the cooling is affected, as will insure a desired ultimate molecular condition in the object.

The invention has for its object, toprovide an improved means for rotating while supporting and advancing,through the chambers or zones of treatment, articles such as rods, tubes or the like,- and thereby insure greater uniformity of temperature throughout the material of the object,-during heating or cooling or both heating and cooling, and consequently a more homogeneous ultimate characteristic in the finished article.

The invention resides in a novel construction of the guiding, rotating and advancing elements forming part of the apparatus which feeds the article through the furnace; which said elements are characterized by V- shaped grooves through which they receive the articles; and which said grooves, regardless of the diameter of the cylindrical articles which they receive, impinge against the articles at two points only, which points of contact are at identical radial distances from the center of rotation of the grooved element, and therefore impart their drive without slipping, which is an important consideration in avoiding rubbing or roughening of the surface of the articles which would result from surface friction at furnace temperatures.

The invention is carried out preferably through means of the conventional type of heat treating furnace, having brick side walls and arched refractory roof, and equipped with a series of shafts or rolls extending from side to side of the furnace, and carried on bearings outside the furnace walls and having mounted thereon, within the heating chamber, suitable shafts, sheaves or wheels with V-shaped grooves in which the objects such as tubes, mandrels, rods, or the like may be guided, rotated and advanced. One or more of these grooved carriers may be mounted upon each shaft, depending upon how many objects it is desired to run side by side through the furnace and the shafts on which these carriers are mounted are spaced as closely throughout the length of the furnace,

as may be necessary toprevent the treated parts from sagging between carriers at the higher temperatures. If these carriers were placed in the conventional mannerwith their axes at right angles to the longitudinal axis of the furnace, that is, perpendicular to w the direction of motion of the treated objects, then the objects would move directly through the furnace and be subject to more or less uneven heating due to the impossibility of havingall parts of the furnace upto 55 the same temperature and due to their contact with carrier mechanism which may even not only obstruct heat radiation and convection, but be at a sufficiently different temperature to control heat of the objects.

Consequently the conveyor shafts are placed at an angle to the furnace axis or to the direction of motion'of the articles to be conveyed, so that the objects under treat ment will be carried through with a spiral motion, in that they will rotate on their own axes while progressing in the direction thereof. The angle of these shafts may be only a few degrees from the perpendicular to the furnace axis or it may be as much as 45 degrees and in some cases even more. The greater the angle the more rapidly will the conveyed elongated articles be rotated during their passage through the furnace.

n the accompanying drawing, in which the preferred as well as a modified embod1- ment of the invention are shown by way of illustration,

Figure 1 is a'vertical longitudinal section of a conventional heat treating furnace to which the preferred form of the invention is applied, the section-plane being indicate by the line la: la: in Figure 2.

Figure 2 is a horizontal section of the same.

Figure 3 is a detail view showing. one design of V-shaped groove useful for realizing the purposes of the invention.

1 represents an arch, 2 a side wall, and 3 and 4 the doors of a heat treating furnace. For feeding through such a furnace, objects such as rods, tubes, mandrels and the like, it is common to provide conveyor rollers in the heating and cooling zones, as well as in advance of the heating zone, so that objects delivered upon the advance rollers will be passed into the heating zone, thence thru the coolin zone, to the point of delivery.

In t e present invention, to properly subject objects thus fed thru the furnace, uniformly, to heat transfer, that is to say, transfer of heat to an object in the heating zone, and transfer of heat from an object in the cooling zone, the feeding rolls are so constructed and arranged that they will not only advance the objects but will impart rotation to them on their axes, commensurately with their advance thru the furnace. This is accomplished by so locating the rotary feeding members that they will have planes of rotation which are at a substantial angle to the direction of feed; in other words, the direction of rotation which involves both a forward and a lateral moment.

Thus, shafts 5 carrying grooved rollers 6 at intervals correspondin substantially to the spacing of the lanes of travel of the objects thru the furnace, extend from side to side of the furnace and are supported on bearin 7 outside of the furnace walls, but the pair of bearings 7 for a given shaft are relatively offset, longitudinally, such a distance as will present the shaft 5 at a substantial angle to the longitudinal axis of the furnace, with the result that when an object X which is to be heat treated is fed longitudinall thru the furnace, it will be given a gra. ual rotation upon its own axis as well as an advancin or feeding movement, and all portions of tie surface area of the object will be successively presented toward the varying heating influences and will receive like treatment. For instance, since presentation toward the intensely hot arch and side walls of the furnace will result in heat absorption materially greater than that resulting from presentation toward the several suporting and feeding rollers 6', there would be in an object passed thru without rotation, a longitudinal zone on the underside of the object, raised to one temperature, whereas the upper and adjacent portions of the object would have attained a temperature of a materially different degree, and as a result, the object would have a different quality of metal along one side than that attained along the other side of the piece; and such differences in temperature would, in many instances, be sufficient to produce distortion of the object being treated. Again, metal may attain, in passing through the furnace, a temperature which would render it sufficiently soft to sag between feeding supports. By constantly rotating the object as it passes thru, distortion arising from either of the causes named, is constantly being corrected.

The shafts 5 may be rotated in unison by any suitable means, such for instance as the screw 8 extending across worm wheels 9 on the respective shafts.

The grooves of the rolls 6 are of V-shape so that articles of different diameters may rest therein in contact with but two points on the sides of the grooves instead of three points as would ordinarily occur with a cylindrical article resting in a concave of greater radius than the article, and with the axis of the article at other than a right angle to the axis of a roll. It is important to have points of contact on the roll at equal radial distances from the center of rotation of the roll in order to avoid slippage or friction which, when the articles are at very high temperatures, has the effect of roughening the surface and spoiling the work. As shown in Figure 3, the carrying element may be provided by forming V-shaped grooves in a roll of suitable diameter, as distinguished from having individual rolls mounted upon shafts.

From the foregoing description it will be seen that this invention contemplates a rotor for turning, guiding, and advancing any elongated cylindrical or substantially cylindrical objects, typified by a rod, which rotor has its saddle or peripheral recess, through which it receives and confines the object, constructed as a V-shaped groove, which causes contact between the rotor and the object to be limited to two points equally distant from the axis of rotation of the rotor by reason of the faces of the groove being symmetrically related to a medial plane of the rotor perpendicular to its said axis; the rotor being constructed with means whereby it may be rotatably mounted with its axis of rotation fixed, or in other words with its said medial plane fixed at a substantial angle to a desired path of advancement of the rod, or the like, through the furnace, so that the two points of contact are, respectively, forward and rearward from a radial plane of the rotor embracing its said axis, and therefore, in addition to the identical forward components in surface movement at each point of contact, have an upward component at the contact point on one side and a downward component at the contact point on the other side, which together develop the rotation of the cylindrical object (typified by the rod) when lying in its intended path of travel and whereby slippage between the supporting rotor and the hot object, which is particularly subject to surface impairment because of its temperature, is reduced to a minimum; and the invention further contemplates a plurality of these rotors in their aforesaid angular positions, so related that they will simultaneously receive the rod in their V- shaped saddles while lying in the direction of desired advancement through thefurnace.

I claim: t

1. A rod turning and guiding carrier for heat treatment furnaces, comprising a rotor and means rotatably mounting said rotor with its axis of rotation fixed at a substan tial angle to a predetermined path of advancement of the treated object through the furnace; said rotor being constructed with a ripheral groove of V-shape forming a sadle adapted to receive cylindrical articles of different diameters and adapted to contact with all of such articles at points which are but two in number and equally distant radially from the center of the rotor.

2. A rod turning, guiding and forwarding carrier for heat treatment furnaces, comprising a rotor constructed with a peripheral groove of V-shape with the sides of the groove symmetrically related to a medial plane perpendicular to the axis of the rotor; said rotor having means through which it is rotatably mounted and fixed with its said medial plane at a substantial angle to the direction of advancement of cylindrical objects which it supports, thereby causing said objects to contact with the defining faces of the groove at equal distances from the center of the rotor but respectively forward and rearward of a radial plane including said axis, whereby slippage of the driving contact between the rotor and its supported object is reduced to a minimum, and while both contacts impart a forward drive, one contact imparts an upward and the other a down ward drive, causing rotation of the object.

3. In combination with a heat treatment furnace, a rod turning, guiding and advancmg rotor mounted in said furnace with its medial plane perpendicular to its axis of rotation at a substantial angle to a desired path of advancement of objects through the furnace; said rotor having a V-shaped peripheral groove with the faces of said groove symmetrically related to the said medial plane.

4. In a heat treatment furnace, a plurality of rod turning, guiding and advancing rotors having V-shaped peripheral grooves and mounted for rotation in positions which adapt them to simultaneously receive and hold a cylindrical object in a predetermined path of travel through the furnace, but with the medial planes of said rotors perpendicular to their axes of rotation at substantial angles to said path and the defining faces of their grooves symmetrically related to said medial planes and imparting identical r0tational and advancing drive to the treated object at two different points equi-distant from the axis of rotation of the rotors and on opposite sides of the vertical longitudinal plane of the object.

Signed at Chicago, Illinois, this 10th day of August, 1927.

FRANK A. FAHREN WALD. 

